Price: $70.00
Pros: The beer is ready to drink now! Very easy to use. 1 trigger for gas and 1 trigger for beer. Less complicated than a Counter Pressure Filler.
Cons: The beer is ready (brrrp!) to drink now! Another piece of equipment that makes bottling beer more convenient but is not "really" necessary.
Recommended? Yes

Comments: I like it. Bottled 30 gallons of beer since purchasing. This is a great bottling tool.

The key to force carbonation (I believe) is get the beer as cold as possible when bottling. Some say chill the bottles which does help reduce the foam. I've tried room temp and placing them in an ice water bath while filling. Helps a little when they're colder but not a show stopper if you can't get the bottles cold.

Less complicated than a Counter Pressure Filler. The Beer Gun is about the same price as a DIY Counter Pressure Filler assuming you purchase all the parts new.

On the down side; more equipment.
You have to keg the beer and force carbonate and that's more equipment.

Pros: Easy to use one handed
Cons: Small clip at end and spring may rust
Recommended? Yes

Comments: A great tool. I prefer to keg all my beer and force carb. This lets me put my newest beer on tap and bottle what's left of the old keg. I love it! RichBrewer is right, 3psi is perfect.

Pros: Bottles have very little foam in them when they are filled. The Beer gun is very easy to use and the directions are straight forward.
Cons: You need to keep your empties in the fridge to keep them at the same temp as the beer. I spent a lot of time sanitising foil strips to place over the empties before I put them in the refrigerator.
Recommended? Yes

Comments: I love this thing! I played with it a bit and found out that mine worked best with a dispensing pressure of 3 PSI. The bottles filled quite nicely with very little foaming.
It was a bit pricy for the gun and the hardware I needed to set it up but I'm very glad I did it.